Amplitude-Based Analysis of QED Radiative Corrections to Electroproduction of $\eta$-Mesons on Protons

TL;DR

This paper develops a formalism for radiative correction calculations in eta-meson electroproduction on protons, extending previous methods and providing numerical results relevant for Jefferson Lab experiments.

Contribution

It introduces an extended formalism and the EXCLURAD code for radiative corrections in eta electroproduction, including detailed numerical results for experimental kinematics.

Findings

Cross-section correction factor varies up to 30% in the resonance region.

Beam-spin asymmetry is suppressed by 15-25% at specific kinematics.

Numerical results are provided for Q^2 from 0.3 to 4.0 GeV^2 across the full angular range.

Abstract

A formalism for radiative correction calculations in exclusive $\eta$ electroproduction on the proton is presented, extending the treatment developed for the pion channel. The EXCLURAD code is used in the radiative correction procedure with EtaMAID-2023 multipole amplitudes. The cross-section correction factor $\delta$ varies by up to ${\sim}\,30\%$ across the resonance region $W = 1.49$-$2.0$ GeV at $E_{\rm beam} = 6.535$ GeV, with a local maximum near $W \simeq 1.66$ GeV driven by the $S_{11}(1535)$ and $S_{11}(1650)$ resonances. The beam-spin asymmetry is suppressed by 15-25% at the same kinematics. Numerical results covering $Q^2 = 0.3$-$4.0$ GeV$^2$ and the full angular range are provided for kinematics relevant to CLAS12 experiments at Jefferson Lab.